I see it all the time – some new blog post detailing how to sync your Google calendar and contacts to somewhere, usually to the iPhone, using some new 3rd party service or crazy trick. Many people suggest NuevaSync to sync directly to the iPhone, or using CalDAV to get your calendars to iCal so they can be synced through iTunes.
Fact is, they are missing a key feature of Google apps that lets you sync to a lot of places, including the iPhone, directly and with push updates – Google supports Microsoft Exchange for both contacts and calendars.
With the Exchange support, you can get push updates to any device or application that supports Exchange, including Outlook on the desktop and the iPhone with v3.0 software and above. It doesn’t get around syncing to iCal (unless you’re already on Snow Leopard, which supports Exchange out of the box), but it’s damn good for mobile devices.
Here are the instructions for setting it up on the iPhone, and you can use the server settings from there to set up any other device/app that supports Exchange.